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Friday, May 30, 2008

I'm reading Chapter 11 ("Milliwatts and Miles") of the book "The History of QRP in the U.S.; 1924-1960" by Ade Weiss, W0RSP. What a gem this book is! I find it particularly inspirational that a book of this high technical level was written by someone with a PhD. in Renaissance Literature. Thanks Ade!

Tuesday, May 27, 2008

On Saturday 24 May I connected my newly acquired K1EL keyer to a little homebrew 10 meter beacon transmitter that I'd built about 10 years ago. (The transmitter is based on the "Lil Slugger" design by Doug DeMaw -- about 1 watt out.) Ten meters seems pretty dead these days, so when I turned the thing on and put it on the air, I had the feeling that no one would hear me. It sort of felt like throwing a message-in-a-bottle into the ocean. I put my e-mail address in the beacon transmission. I've had the thing on the air very intermittently over the last few days.Imagine my surprise when this morning my e-mail box contained a message from Andre in Germany. He'd heard the beacon in its first day on the air! Wow!

During daylight hours I can hear beacons from all over Europe on ten.

I have left space in my "beacon box" for a very QRPP 30 meter transmitter. The K1EL keyer will generate QRSS. Where is the best place to get a crystal for 10.140 Mhz?

See if you can hear my beacon on 28.240 MHz. I'll have it on during daylight hours (Italian daylight hours).

Tired of listening to The Who or Wagner on your I-Pod? Wouldn't you like to be able to carry withyou the kinds of ham radio conversations that youlisten to while in your radio shack? Tune in to SolderSmoke!

RSS FEED: You can subscribe to the program, havethem downloaded to your MP-3 player, and listen tothem at your convenience. To subscribe, just cut andpaste this URL into your I-poder (or similar)software.http://www.soldersmoke.com/soldersmoke.rss

If you don't have an MP3 player you can just go to thesite below and listen to the latest program (andearlier editions) using the audio software on yourcomputer.

http://www.soldersmoke.comAll the programs are available here. I hope you enjoy the program. Please send usfeedback.73 from RomeBill M0HBR N2CQR CU2JLhttp://www.gadgeteer.us

Tuesday, May 20, 2008

I was up earlier than usual this morning (my Italian ham friends think my schedule is totally nuts!). As usual, I tuned across 80 -- it seems 0430 is a bit too early even for the hardcore fanatics who can be heard starting at around 0530 local. But there was one CW signal distinctly audible: good old W1AW, pounding out code practice close to the color burst frequency.

A bit later I tuned up around 3.8 Mhz, where the DXers hang out. There I heard a familiar call (and voice!) from the homeland: K1JJ. I used to listen to OM JJ on 75 Meter AM. What a signal he has in Europe! The Italians were all saying "Mama mia!" And what an antenna! From JJ's web site (at QRZ.com) :

NE/Europe: Dual quads system. (4 elements total) A two-element quad on a 40' boom at 190' high (63 meters) phased to a second identical two-element quad at 190' high on a separate tower. These two-element quads are spaced 1.17 wavelengths apart from each other, (spaced 100 meters apart) beaming broadside to Europe. The horizontal pattern is narrow, only about 35 degrees wide because of the collinear gain...intended for central Europe. The two quads are fed with equal length coaxial hard-lines that are run into the shack, and connected in-phase. The take-off angle is about 28 degrees, much like a flat, horizontal Yagi at 135' high. The AVERAGE height of the quad loops dictates this take-off angle.

I went out for pizza last night with I0YR, IK0JNI, and IK0ZMH. We had a great time.

I just got a very pleasing dit dah dit from my new K1EL keyer. The board went together quickly. It is a very nice kit. Lots of capabilities in that little thing: beyond the normal keyer function, there is beacon capability. And QRSS! I plan to match mine up with my 10 meter beacon transmitter and my Volkswagen solar panels for a self-contained, solar powered beacon.I may have to buy another one of these for use with my HW-8 -- this keyer may actually cause me to abandon my straight key.

Sunday, May 18, 2008

Just a quick Sunday morning report from Rome: With my 20 meter DSB rig finally tamed, I've been trying to decide which band to build for next. Italian hams just got access to more of 40 meters (now 7.0 -- 7.2 vice 7.1 MHz) so for a while I was thinking of 40. But 40 is pretty quiet at 5 am here, while there ARE stations operating on 80 at that time. So I'm building for 80. Actually I am rehabilitating a DSB rig that I built in London for 40. This morning I changed the coil in the VFO and have it percolating nicely from 3.55 -- 3.8 MHz.

I've been having a great time on 20 DSB. We have a local roundtable in Rome each night at 2030 local. I0YR, IK0JNI, IKOJMH, and I0ZY are all regulars. Very FB. Yesterday afternoon I worked Renato IZ1MJU up in Torino. He too was running a homebrew station. It is rare to have an HB-HB qso, especially on phone.

Right now I am tuned to my old stomping ground on 17 meters, listening to my old friend Chris, SM0OWX. I'll have to get that 17 meter rig going...

I should have another SolderSmoke podcast next weekend. I've added some stuff to the blog page: Check out the slide shows (2 of them) and the Dilbert Knack animations.

Saturday, May 17, 2008

As all of you probably know, LB Cebik, esteemed antenna expert and mentor, recently passed away. This morning I happened to find his entry on the wonderful "Novice History" web site:http://www.novice.bappy.com/index.html

Note what LB says about "the ham spirit."L.B. Cebik, W4RNL (WN4RNL, 1954)I was licensed in 1954 as both a Novice and a Tech, sincethen you could take both exams in one session andprivileges were separate. (W1APS/WN1APS)I got onthe air for the first time with a ham a couple of blocks away,an fine old timer.

However, I got key fright half way through. My dad,James S. (Jim) Cebik, came to my rescue and finishedthe contact, although he had not touched a key inover 20 years.

Jim Cebik had been 1ATG and later W1BUK in the late1920s and early 1930s (and wrote a few articles onhis experiments). He gave up amateur radiowhen he married in the depression years. Relativeparts costs were high, and family came first. In fact,he rarely mentioned amateur radio, and myentry was independent via some high schoolcomrads and a cousin. But he had not forgottenhis CW or key skills and saved me fromembarrassment on that first day. I returned the favorby renewing his interest in amateur radioand about 1964, he was relicensed and obtainedhis old W1BUK call, which he used for very manyyears. He died in 2002 in his high 90s.

So my Dad was a part of my Novice beginningin amateur radio, and I strove to send CW witha straight key so that one could not tell it froma keyer.

He remains a strong part of my effort. He notedthat the ham spirit is to give, if needed, the shirtoff one's back to a fellow ham and to expect--notits return--but rather that it be passed on to thenext ham who needs it.That is the spirit of my web site.

My Novice days were a joy, and I have beenpleased to carry my father's amateur radio daysinto everything that I do.

Friday, May 16, 2008

A few episodes back I was talking about the old QST articles in which amateurs were extolled to focus more on efficiency and technincal quality, and less on high power and brute force. Wes, W7ZOI was kind enough to send me some of these articles. Here is the header for one of them.

Thursday, May 15, 2008

I always liked the descriptions of the ingenious homebrew stations used by Indian radio amateurs. This morning I came across VU2LID's site and found this:

A typical Indian QRP station will use a modified AM broadcast (BC) receiver, for the receiving part. The transmitter will usually have a final RF power amplifier using BD139 (or some power MOSFET like IRF530), driven by a Variable Frequency Oscillator (VFO) and chain of buffer/driver amplifiers (2-3 stage). Most of the stations use Amplitude Modulation (AM). Commonly available medium power Hi-Fi audio amplifier modiles using integrated circuits (like the TBA810), driving a modulation transformer forms the AM modulator part.

Tuesday, May 13, 2008

It's 5:30 am. I'm in the shack with a cup of coffee. The only sounds are birdsongs from the window and an Italian 80 meter SSB QSO from my Drake 2-B. Life is good.

And it got better when I found the rig pictured above. It is the work of Andrea IW9HJV and Johnny IW9ARO, two obvious victims of "The Knack" from Sicily.

It is a beautiful 20 meter SSB transceiver. And it uses just 5 tubes. While it doesn't have the bi-directionality of the BITX-20 (you can't really do that with tubes) it does share the BITX-20's simplicity and elegance of design.

In the course of testing my 20 meter DSB rig, I discovered that the chart I prepared for my

W7ZOI / W7PUA power meter had some problems. In my first effort to get some calibration points, I used a simple diode and cap peak reading signal probe to measure voltage across 50 ohms, but I may have neglected to convert from peak to RMS before calculating the power. That would certainly mess up the chart!

This morning I used my old Heathkit SG-8 signal generator and my HAMEG (20 Mhz) 'scope to get a couple of points for my graph of the response curve (line) for my meter.

I drew the new line, then used my trusty HW-8 at 1 watt to see if my chart was accurate. It was right on the money!

I look forward to happily measuring milliwatts with this very FB piece of test gear. See the June 2001 issue of QST for more details. Thanks to Wes and Bob for the great project. And thanks to Thomas in Norway for sending me the AD8307 chip.

Monday, May 12, 2008

I'm really in the dark ages on this subject -- I usually just draw something by hand and then scan it. Others (like JF1OZL) have good results with this technique. I don't. So I was glad to see this suggestion from Farhan on software that can be used to draw professional-looking schematics:

"i have used something called schemat.zip available freely on theinternet. it consists of a bitmap file with all the symbols that weuse in ham radio. i open it in ms paint, start a new copy of ms paintand start selecting the symbols from the first ms paint window andpasting it into the fresh ms paint window. Remember to UNSELECTOPTIONS->DRAW OPAQUE. Sorry for the caps, but it is important. You canuse the line tool to draw the 'wires' connecting individualcomponents. holding the shift key down while drawing lines forces thelines to come out perfectly horizontal or vertical."

Saturday, May 10, 2008

Every once in a while I do a Google search on "QRP DSB." This morning the search yielded a real gem: Miguel PY2OHH has a site that reminds me of JF1OZL's legendary HB pages.

There are many projects on Miguel's site, but it looks to me as if the most well-known and widely reproduced is his "Maritaca" 40 meter DSB transceiver. Miguel's page has photos of versions of his rig built by other Brazilian hams, and YouTube carries videos of several of these projects.

Miguel has been kind enough to translate into English the descriptions of many of his projects, but even on those that are not yet translated, we can all see what he has done through the universal language of the schematic diagram.

Thursday, May 8, 2008

Dan's web site reports that there was a bad accident, and that his business is temporarily closed, but that "Dan will be back." Let's all wish Dan the best of luck. Many of us depend on him to keep our junk boxes well-stocked. I was just getting ready to send him an order.

I am an early riser -- I am in the shack with coffee cup in hand each day by 0515. At sunspot minimum, that's just not the best time to be on the air. But 80 meters has come to my rescue. I've discovered that I'm not the only ham in Europe who gets up early. The CW guys are there first; phone ops seem to sleep in a bit. With my HW-8 and end-fed wire, I work a few stations each morning. (Today I worked TK7C on Corsica. ) Later on I listen to some AM enthusiasts who meet on 3705 kHz. And there is some great Italian tech talk (mostly about old tube rigs) on 3643 kHz. I plan on building an 80 meter DSB transceiver. (I've joked with Michael, AA1TJ, that on this project I plan to design first that THEN build.)

I've the LTSpice Yahoo Group for some guidance on how to model bifilar and trifilar toroidal transformers in LTSpice. I'm not sure I'm doing this right.

I'm not crazy about contests, but they can be useful for a QRPer looking to work a lot of stations in a short time. I was on 20 DSB today with the HB rig. Worked UU5WW, US0LW, OH3OJ, IQ0OEF, LY6A, GX0WSS/P, ES5GP...

Took a break in the morning and went out for coffee with my wife. On the way back we stopped in a charity shop/flea market. Found an old Collins rig that looks like BC-348 sitting on the floor. I reluctantly left it there, but I will alert the local hams.

Saturday, May 3, 2008

Our friend Ramakrishnan VU3RDD suggested that I put GadgeteerNews into blog form so that SolderSmoke listeners could subscribe to it and be alerted to updates. Great idea. Here it is. (All the old stuff is here too.) Check out the videos!

I want to update this blog every few days. I hope that it will serve as a useful adjunct to the SolderSmoke podcast. I also hope that it will facilitate communication within the worldwide SolderSmoke community. Please let me know if you have any trouble with it, or if you want me to change any of the settings.

Let me start by pointing you to a very interesting new site. In SolderSmoke 81, I was whining about computers, and praising the virtues of HARDWARE Defined Radios. Perhaps in response, Nicholas in Sydney sent me this link to an on-line Software Defined Radio. Very nice. Multiple listeners can monitor 80 and 40 meters. You can change the filter settings. And be sure to check out the associated web pages for a look at the VERY UGLY (construction technique) hardware associated with this Software Defined Radio. http://websdr.ewi.utwente.nl:8901/

Friday, May 2, 2008

February 16, 2008 The Rome operating position. The HW8 is currently my main rig. The Drake 2-B awaits new tubes from AES. The copper-clad box is a homebrew 20 meter DSB transceiver using ceramic resonators and (mostly) NE602 chips. It awaits sunspots, but has yielded some great local QSOs in Rome . You can see my homebrew antenna tuner behind the straight key (with Vibroplex base). Also check out the very old Hi-Z headphones.

February 10, 2008 Amazing K7AGE Video of HARP HF MoonbounceCheck this one out. Not exactly QRP (!) but very interesting. At first the reflection signals are hard to hear, but hang in there,they get a LOT stronger, and you can see them on Randy's computer screen.

January 25, 2008VIDEO: WA7MLH Builds A Superhet ReceiverJeff, WA7MLH, assisted in the construction of many of the projects in "Solid State Design for theRadio Amateur" (SSDRA). I always liked the "ugly" "real world" look of his projects -- in contrast, some ofprojects in the Handbooks looked like they'd emerged from a NASA clean room, not a ham shack. Continuingin this tradition, Jeff has produced a very interesting YouTube video on a superhet receiver that he put togetherlargely with parts and circuits that were already on his workbench. FB.Also be sure to check out Jeff's web site. The projects are both inspiring and intimidating! I really like theaudio explanations that he has alongside the photos. Thanks Jeff! WA7MLH's Ham Radio Web Site----------------------------------------------------------------------------January 24 2008 Steve, G0FUW, was recently listening to SolderSmoke at this location.That's ZD8, Ascension Island in the South Atlantic. Check out the antenna farm. Thanks Steve!

January 12, 2008SPRAT 99 (Summer 1999) has an article by Leon Williams, VK2DOB, that I thinkdoes a great job at graphically describing how a mixer circuit produces both sum and differencefrequencies.

January 5, 2008As part of an effort to understand mixers, I built a little circuit in LTSpice. Just two audio signal generators and three resistors. Surprisingly,this thing seems to produce a "beat" or difference frequency. We've been discussing this on QRP-L and the G-QRP list. Here are somescreenshots of my LTSpice simulation. In the waveform shot, you can see how the phase differences of the two input waves combine toproduce the beat. I subsequently learned that this is not like a mixing product. It is not "extractable."

January 4, 2008SCI-TOYSStewart, G3YSX, sent us the URL for a very interesting web site. Check out theMorse communicator project in the computer section.SCI TOYSFor similar stuff, check out "Gonzo Gizmos," available from the Gadgeteer bookstore (above).

January 2, 2008HOMEBREW TUBESI really liked this video. The guy who made it has obviously mastered multiple difficultcrafts, including glass blowing, metal work, chemistry, electronics... Also, the videoitself is very well done, with really nice music in the background. Don't miss this one.Video on homebrew tubes (valves, firebottles, etc.)

You guys are probably sick of hearing about my appearance in the Bollywood movie "Cheeni Kum," but it just keeps gettingbetter and better. In the course of trying to post the trailer for the movie, I discovered that I not only made it into the film, but that I also made it into the trailer! On the You Tube clip, you'll need to put the video on "full screen" (click on the little box in the lower right of the video screen -- next to the volume control) then freeze the action at around 54 seconds. I'm the guy in the blue shirt in the Starbucks on the left of the screen. In SolderSmoke #73 I'll tell you about a connection between all this and the BITX-20. By watching the trailer you'll also get a sense of what modern Bollywood is all about.Bill in Bollywood! Cheeni Kum Trailer! I'm in it! Check it outVATICAN ANTENNASLooks to me like some sort of Streba Curtain array. This thing is only about 15 miles from our place in Rome. I want to visit!Vatican Radio's HUGE SW Antenna Farm (near Rome)Google Earth Location Info Look a bit north of the town of Santa Maria di Galeria and you should see the antennas.

Google now allows you to create "gadgets" that people can place on their individualized iGoogle home pages.For example, on my iGoogle page, I have a map that constantly shows the position of the International Space Station. I also have various news service, weather reports from places of interest, Dilbert, etc. Yesterday I created a Google Gadget for SolderSmoke. I'll use it to announce new editions of the podcast, updates of GADGETEERNEWS, etc. Be sure to include it on your iGoogle page. Google says it will appear in their directory within 10 days (search for SolderSmoke). If you can't wait that long, e-mail me and I'll send it to you.

-----------------------------------------------------------2 June 2007Farhan's BlogWe're all very fortunate that our friend Farhan has set up a Blog. It is already full of interesting info. I especially liked his first article on minimalist tools for the homebrewer. Check it out! Spread the word! Post comments on the blog.FARHAN'S BLOG--------------------------------------------------------

12 May 2007HELP WANTED: SOLDERSMOKE CORRESPONDENT FOR DAYTON HAMVENTION AND FOUR DAYS IN MAY The sad fact is that most of us won't be going to the big hamfest and the Four Days in May event. But if you are going, you can help your Dayton-deprived SolderSmoke brothers. You could become SolderSmoke's correspondent in Dayton. We're looking for someone who would be willing to record some short audio segments that would be included in the show. Segments 5-10 minutes long would be ideal. Interviews with homebrew and QRP leaders would be very interesting. Just send me the .wav or .mp3 files and I'll put them on the show. Perhaps just figure out how to use that record feature on your MP3 player, or bring along a small audio recorder. We don't want the Hamvention clogged with multiple SolderSmoke journalists, so we will be selecting only one or two OFFICIAL correspondents. If you are interested in doing this, send me an e-mail. Thanks!-----------------------------------------------------12 May 2007KX4OM's excellent page on the W7ZOI power meter

----------------------------------------------------6 May 2007SolderSmoke Book of the Week: As discussed on the podcast.

----------------------------------------------------25 April 2007SEMI-HOMEBREW 100 Mhz Digital 'Scope -- for $78Interesting Oscillosope project-------------------------------------------25 April 2007FMLA SAMPLEI mentioned the Frank Jones "FMLA" series of radio fiction article by Michael Hopkins, AB5L, SK. Here's a sample. You can find more via the QRP-L archives. ... Frank is all homebrew. His receiver is unshielded outside, but built around a central square of aluminium that houses a Velvet Venier dial thru the front panel and some tubes I did not recognize jutting horizontally on both sides of the box where coils also plug in. The transmitter is a multi-stage affair on a piece of particle board. The tubes are vertical here, and the bench was littered with brown Hammarlund coils labeled 5, 10, 20, and 80. The 40M coils were in place and Frank worked a few stations at dizzying speed with a J-38. He never used the same call twice, and when he offered me a turn, I declined. The only transfomer in the place was on a small screen modulator attached to a pair of TH-100s labeled "PA" in the rack below the new-as-tomorrow computer. He seemed to be taking all his DC off the three-wire service line that entered thru a large piece of plastic DWV pipe and where, in turn, a run of fiberoptic snaked out and disappeared along a railroad right of way. I eased toward the back of the trailer, but Frank ignored the hint and suggested lunch. As we took our leave the WARmon resumed his post at the gate and Zack began burrowing a small hole in a sack of Vital Varmit Dog Food. I never saw a canine. Frank drove to a a place called Pancho's Villa where he was well known and greeted with cries of "Vato!" I agonized with the menu's contorted Tex Mex, but Frank ordered menudo, rice and beans like a native. Indeed, in this enviornment his double-breasted suit did not seem so out of place, and when he parked, the Frazier drew a cadre of youths saying "Looks Charp" and "How High will it jump/" "These are good people," said Frank, " and they recognize the value of improvosation." "They are not like modern hams who cannot homebrew a CPO without a PC board," he continued and , once again, he warned that when, as he says,"the balloon goes up" a lot of "KA this(s) and Vanity thats" won't be in those chosen to retake 5 Meters. On a more personal note he said my efforts at converting an old SCR-522 receiver were a good start and, when we left and said goodby at the Airflow, he procured from a plastic storage case under the napping Zack a Standard Coil tuner from a TV set long departed. "The old VHF Handbooks show how to make these into a converter," he said, "See what you can do with it." I reflected on the way home that while Frank is truely a nut, he is also like the hams I knew when I was a kid. Those were guys who could "fix a radio" as the neighbors said, and we are someting else. Toying with the tuner, I found a note from Frank inside. "Don't change the Channel 2 part," It read.

73 de ab5L, michael in Dallas, student of Six Meters' Golden Age, 1957-58, and two of its jewels: Tecraft and International Crystal ham products. Michael N. Hopkins Box 226841 Dallas, TX 75222 MNHopkins@Juno.com---------------------------------6 April 2007ITALIAN QRP CLUB CARRIES ARTICLE BY MIKE, KL7RIvan, G0BON, alerted me to the fact that the I-QRP club has included oneof Mike's projects in its April 2007 magazine. Mike would have beenvery pleased. Grazie! By the way, the magazine looks very nice. I am really grateful to Ivanfor sending me this. I am studying Italian now, and the magazine lets me combine language study andQRP reading.Mike's article in the I-QRP journal.-------------------------------------------------------6 April 2007 NJHR 040107 CRIMINALIZES SOLDERING IN THE HOME! ?The most important thing about this law is the date on which it was announced on SolderSmoke (note the number of the bill). Here wesimply participating in an old April tradition in ham radio. I hope the Trenton post office recovers from the flood of angry letters! ---------------------------------------------------------------6 April 2007 PA0CHN HOMBREW SSB TRANSCEIVERMike, EA8EQ, alerted me to this one. Very interesting. PA0CHN Homebrew Rig----------------------------------------1 April 2007FO-29 SATELLITE: FEATURED ON THIS WEEK'S BANDSWEEPBackground info on the satelliteThanks to Ray Benitez, M0DHP, for this first ever guest edition of Bandsweep. ------------------------------------------------------------1 April 2007JEAN SHEPHERD, W9QWN, K2ORSThrough his nightly program on WOR-AM in New York, I got interested in ham radio. Through this site,you can listen to the old programs. Use the search feature to get to the shows that deal with ham radio.I suggest plugging "Jean Shepherd" into the "artist" field, and "radio" into the "topic" field. The Jean Shepherd Audio Archives-------------------------------------------------------------26 March 2007STORE THAT SELLS PARTS FROM THE SPACE PROGRAMIf you don't feel the urge to visit this one, you are not a gadgeteer-------------------------------------------------------------March 25, 2007

JEFF DAMM'S INSPIRATIONAL WEB SITEGreat HB stuff from an SSDRA collaborator. Be sure to check out the audio!------------------------------------------------------March 25, 2007ABOUT SOLDERSMOKE'S NEW MUSICBeginning with #50, we are using custom-made theme music provided by Mark "Moj" Johnson. Mark explains how it was made: "In the homebrew spirit, I tried to make all the sounds with instruments which I had soldered together myself. These were a Formant music synthesizer designed by C. Chapman from the Dutch/British "Elektor" magazine, circa 1977, and a FatMan synthesizer kit from PAiA Electronics. I play them through an ancient Kustom 200 guitar amplifier, which I've caused to smoke at least twice. The beginning is my K2 being powered on and tuned across 80 meters. I cheated and used a real gong at the end which a good friend went to the trouble of finding and buying in China, but I fed the sound through a PIC Polywhatsit designed by John Becker and described in Britain's "Everyday Practical Electronics," December 2001. If anyone wants to sing along, it seems to me that the words are: ' - Sol-Der Smo-Oke, - Sol-Der Smoke (repeat over and over) ' Music, like all home-brew, is never truly done. Next time I'll try to get a theremin working again - there's a radio-circuited musical instrument!"---------------------------------------------------March 24, 2007

ANTIPODAL MAP TOOLFind out what's exactly on the other side. http://www.ubasics.com/dighole/-------------------------------------------------------March 3, 2007

MELTING SOLDER (VIRTUAL AND REAL!)I'm continuing to work with feedback amps, first in LTSpice and then on the actual workbench. After building the second stageon this amp, I noticed that I wasn't getting as much output in the real version as LTSpice was predicting. Poking around a bitwith my 'scope (the real one!), I noticed a lot of RF on the 12V DC line. This was before I added the C7 bypass cap. After I put C7 in, the RF on the Vcc line disappeared and output was pretty much as predicted by LTSpice. I think this illustrates thesthengths and weaknesses of the simulators. Even without C7 in the Spice model, the model showed no RF on the 12 V line. But in the realworld it was there. Here's the circuit so far. I am feeding it with the output of ceramic resonator oscillator.

-----------------------------------------------------------------------------------------28 February 2007HOMEBREW CONTESTSFame and fortune could be yours! Check out these two homebrew competitions. Thanks to Frank, VK2AKG, for alerting us to them.Spectrum IEEE contest

New South Wales contest----------------------------------------25 February 2007:SolderSmoke 47It was with a heavy heart that I recorded the first ever solo edition of SolderSmoke. Irealize that it isn't even remotely as good as the earlier editions, but I was getting a lot of "I really miss SolderSmoke" messages, and I could almost hear Mike urging me to "do another one." So there it is. I'll try to line up some regular guests (the episode with Farhan was very popular) so hopefully soon we'll see the end of my mono-tone monologues.----------------------------------------------------------------------21 February 2007GREAT BITX20 SITE (WITH VIDEOS)Leonard, KC0WOX, has put together a great site describing his experiences with the world famous BITX20 transciever (from India). He hastwo videos, one describing AM and DSB modulation, and one about building crystal filters.Click here to check it out. The video links are at the bottom.--------------------------------------------

11 February 2007 OUR FIRST ANIMATION Billy and I tried our hand at making a simple animated video clip. We're a long way from Disney quality, but it did work!We used a digital camera and Windows Movie Maker. It runs for 4 seconds. Check it out. Billy and Bill's First Amimated Clip!----------------------------------------------------------

10 February 2007GADGETEER BOOKSI just launched an online book store intended to be of interest to Gadgeteer and SolderSmoke fans. Here's the deal: I provide book suggestions and short reviews. If you go to Amazon via one of my links and buy something, Amazon sends me a bit of money for the adverstising. My ambition is to cover the cost of the web hosting and domain registration for Gadgeteer and SolderSmoke. GADGETEER BOOKS -- BILL'S ONLINE BOOK STORE-----------------------------------------------------10 February 2007 Laser computer link On SolderSmoke we talked about using lasers for communication. Here's a neat plan for using ordinary laserpointers to link two computers. Thanks to Hack-A-Day for alerting me.http://www.geocities.com/SiliconValley/Lakes/7156/laser.htm

---------------------------------------------------------------------22 January 2007LTSpice Circuit SimulatorWe've been talking about the LTSpice program. Nick Kenndy, WA5BDU, has some very good info about this amazing programon his web site. Nick wrote a short guide to LTSpice for beginners that I found very useful. Click here for Nick's site.Thanks Nick! -------------------------------------------------------------------------------------------14 January 2007LIQUID OXYGENI just have to share this. We were walking through Chelsea (London) this afternoon , en route to St. Luke's park where we intendedto launch a vinegar and baking soda rocket. I was telling my son about the fuel system used in the Saturn V -- liquid oxygen and all that.He asked, "Dad, can they really turn oxygen to a liquid?" At that moment, we tuned the corner and came around the back of MarsdenHospital. I looked up and saw in front of us a huge tank marked "LIQUID OXYGEN." Wow, perfect timing. I eve had the chance topoint out that widespread availability of pure oxygen in hospitals is an Apollo spinoff. (Our rocket launched spectacularly!)----------------------------------------------------------13 January 2007MY EXPERIMENTS WITH FEEDBACK AMPSI've been trying to improve my understanding of amplifier design. I start with SSDRA and EMRFD, then do some initial design on paper,then proceed to a simulation in LTSpice, then I actually build the thing on the workbench. There is a lot of complexity in even a very simpleamp. Wes, W7ZOI, (one of the authors of SSDRA and EMRFD) has been kind enough to help me, and he sent comments on my latesteffort. Here they are, in .pdf form. Thanks Wes! Wes, W7ZOI, comments on feedback amp

4 January 2007GOOD CONDITIONS ON 17 METERSI started the new year off with a touch of the flu, but every dark cloud has a silver lining. I was able toget on 17 meter phone when conditions were good. With my 5 watt homebrew SSB transmitter I managed totalk to WB3ANT in Pennsylvania on 4 January. It had been a long time since I'd had a transatlantic contact.I've also been hearing lots of DX on 17 during the day, including Australians and Falkland island stations.-----------------------------------------------------------

22 December 2006MIKE's LT SPICE INTRO VIDEOCheck out Mike's very informative video explaining how to use the (free!) LTSpice circuit simulation program. Besure to click on the little green arrows when they appear (they just pause the video).Mike's Intro to LTSpice video-----------------------------------------------------------------------

17 December 2006CRYSTAL MADNESSIt turns out that the station we are listening to with the crystal radio is Kismat Radio, 1035 kHz in London. It serves the Asian community and broadcasts in a number of languages of the sub-continent. (It is a very nice station, and we enjoying it. The Bollywood music is great!) This morning we experimented with a few different detectors. I pulled out an old galena and phosphor-bronze cat's whisker detector. My son found the sweet spot, but the signal level was significantly lower than that of the germanium diode. Next we tried an LED. No joy there -- I think the threshold voltage for this device is too high for our purposes. Finally, I dug up some "fools gold" that we had bought in the London Natural History museum. With the phosphor bronze cat's whisker, this worked almost as well as the germanium. I have the receiver feeding a little amplified computer speaker. Kismat radio is rocking the shack! ---------------------------------------------------------

16 December 2006CRYSTAL RADIO ADVENTURESInspired by Rick Campbell's minimalist radio post (see below), my son and I built a crystal radio this morning.Just an LC circuit with a coil wound on an old plastic bottle (Re-Nu!) and a variable cap. Germanium diodedetector. Hi Z headphones. Antenna is my 20 meter vertical. AM broadcast stations coming in very loud and clear. Check out the recording at the link below. This was made just by holding the computer mic to the old headset. Is that Hindi?

13 December 2006MIKE'S LTSPICE VIDEOCAST -- RETURN LOSSCheck out Mike's excellent video showing his work on return loss calculations and input/output impedances using LTSpice.Be sure to click on the green arrows when they appear. Mike's file is very skinny -- only 2.5 megs.

Mike's return loss LTSpice video-cast---------------------------------------------------------------------------- 10 December 2006FIRST LTSPICE VIDEOCASTI made a 5 minute video using a video screen-capture program and the circuit simulator LTSpice. In addition to showing how LTSpice canbe used, the video looks at how saturation affects the efficiency of Class C amplifiers. I put the file on YouTube, but the video quality is poor when viewed through that service (it is difficult to see the graph lines in the YouTube version). So I have also uploaded the 26 meg file (.wmv)to the http://www.gadgeteer.us web site.

----------------------------------------------------------------------7 December 2006

BOOK RECOMMENDATIONIf you like SolderSmoke, you'll love Gonzo Gizmos. Lots of great projects, including radio stuff. The author does a wonderful job of mixing construction information with scientific theory. I found my copy in a comic book storein London. Link to Amazon.com on the left.-----------------------------------------------------------------------4 December 2006HOMEBREW TUBES

“A young lad of seventeen, known to possess an especially efficient spark, cw, and radiotelephone station, was discoveredto be the son of a laboring man in extremely reduced circumstances.The son had attended grammar school until he wasable to work, and then he assisted in the support of the family.They were very poor indeed.Yet despite this, thechap had a marvelously complete and efficient station, installed in a miserably small closet in his mother’s kitchen.How had he done it?The answer was that he had constructed every last detail of the station himself. Even suchcomplex and intricate structures as headphones and vacuum tubes were homemade! Asked how he had managedto make these products of specialist, he showed the most ingenious construction of headphones from bit of woodand wire.To build the vacuum tubes, he found where a wholesale drug company dumped its broken test tubes, and where the electric light company dumped its burnt out bulbs, and had picked up enough glass to build hisown tubes, and enough bits of tungsten wire to make his own filaments. To exhaust the tubes, he made his own mercury vacuum pump from scrap glass.His greatest difficult was in securing the mercury for his pump. Hefinally begged enough of this from another amateur. And the tubes were good ones, better than many commerciallymanufactured and sold. The greatest financial investment that this lad had made was 25 cents for a pair ofcombination cutting pliers.That is the spirit that has made ham radio.” From “200 Meters and Down –The Story of Amateur Radio” By Clinton B. DeSoto, published in 1936 by the Amateur Radio Relay League, Inc.West Hartford, Ct.pp 63-64

FEEDBACK AND INPUT IMPEDANCEWHAT BILL WAS STRUGGLING WITH ON SOLDERSMOKE #42

I think it was just too early in the morning for thinking about this kind of issue. Why would placing a feedback network between thecollector and the base of a common emitter amplifier decrease the input impedance? This is what I wanted to understand. I thought I did, but then I couldn't explain it. That made me realize that I didn't really understand it.

Understanding came to me today while my daughter was playing on a swing in a London park: Imagine this circuit: Common emitter, NPN transistor. Imagine the input signal in the positive half of the cycle. During this part of the cycle, the input signal will be pulling electrons up through the base-emitter junction. The amount of current that will be generated by a given input voltage will define the input impedance.

Remember that the voltage at the collector is 180 degrees out of phase with the input signal. When the base is in the positive portion of the cycle, the collector is in the negative portion. If we use a feedback network to put some of this negative collector voltage on the base, the amount of current drawn out of the circuit will increase. You have just connected the electron deficient (positive) input signal to the electron rich (negative) collector signal. With the collector to emitter feedback network, the input voltage will pull more current out of the device than it did without the feedback network. More current flowing for a given input voltage indicates that impedance has dropped.

For some reason the explanations in the literature never made it clear to me WHY this kind of feedback lowers the input impedance. Now I understand it. (I hope!)

--------------------------------------------------------------------------------------3 December 2006A FEW THOUGHTS ON MINIMALIST RADIO FROM KK7B(Originally posted on the EMRFD Yahoo group)

If you really want to do minimalist radio, you may want to step wayback and take a look at some very early history. The Pixie circuithas many more components than an early CW station from the eraimmediately after spark.

Rather than starting with the Pixie and trying to figure out what toeliminate, maybe a better approach is to start from zero and decidewhat you need. Combining transmit and receive functions is the lastthing to think about.

Starting with the receiver.... The first thing you need is wire upin the air. The more, the better. If you have the real estate for afull sized dipole on 80 meters, you can collect enough signal energyto hear on a crystal set when conditions are good. I've copied CWsignals on 40 meters with just a dipole, transmatch, a 1N34 diode, agood pair of headphones, and a one transistor Pierce oscillatorrunning on the bench. The leakage from the crystal oscillator pickedup by the antenna beats against the incoming signals. I didn't powerthe oscillator with lemon juice, but I could have (see Bob Culter andWes Hayward, "Lemonized QSO" in March 1992 QST.)

Then for the transmitter, just heat-sink the Pierce oscillator andkey the connection to the load. The shift in load impedance willoffset the crystal oscillator frequency.

A dual pi-net transmatch configuration would take care of theharmonics and allow maximum energy transfer between the antenna anddiode--but I'd analyze it to make sure the harmonic suppression ismore than legal.

So far I count 5 components for the dual Pi-Net transmatch, a 1N34diode, 6 components for the one-transistor Pierce oscillator. Adozen parts, plus headphones, a key, and battery--or some electrodesto push into a lemon.

That would make contacts, but Wes and I have discussed a basic rulefor radios, which is that a station should be able to work anidentical station over a distance of a few miles. It could probablybe done with the above station, but a single transistor audioamplifier running at maximum gain between the 1N34 and headphoneswould make it possible to extract many more signals from the 80 meterdipole. That's another 5 or 6 parts. So now I'm up to about 20.

For a more serious station, I'd probably add two more transistors anda diode, so I could have a separate PA, a balanced mixer, and twoaudio stages. The receiver would end up looking a bit like EMRFDfigure 8.7 with a PA tacked on. That would have about 35 parts, butit would be able to work DX off the ionosphere...about the samecomplexity and performance as many other variations on the theme. Aprevious version of the Pixie from the 1970s was called "TheOptimist."

Unlike Muntz--instead of starting with someone else's circuit andtrying to eliminate parts until I had something that just barelyworks, I'd start from scratch, study EMRFD (and other references too--but in EMRFD all the circuits have been designed and tested) forcircuit ideas, and then start experimenting on the bench, one stageand one component at a time. Since one of the joys of minimalistradios is that they can be understood all the way down to the devicephysics, I avoid ICs. (I particularly avoid cell-phone ICs, which Idesigned for a number of years. It's like working in a sausagefactory--you are much happier if you don't know what's inside.)

Minimalist radio is one of the more interesting design games that weplay using the methods of EMRFD. It's cheap, it's interesting...andas we dig in, we discover that the details can be every bit aschallenging for a radio project with 30 parts as one with 30,000.

Gang, The ever famous NE602's are manufactured in the Philips Semiconductor plant in Albuquerque, about 85 miles north of me. I visited there last summer and had a nice discussion with an applications engineer about the history of the NE602's. Goes something like this:

This long story will prove that NE602 = SA602 = NE612 = SA612 (for those of you who don't want the gory details -hi) The original NE602 was designed/manufactured by SIGNETICS for the 45MHz FM wireless telephone market. A little later, the wafer was redesigned a bit to allow the internal oscillator to operate to 200MHz and the RF to 500MHz. This was redesignated the NE612, and was intended to replace the NE602. However, customers kept ordering the NE602, getting angry at Signetics because their distributors were out of stock, etc. So when they made the chips, they made a jillion NE612's, and labeled some of them NE612 and the rest NE602 to satisfy the users of both parts. This is why contemporary data books show the exact same specifications for both NE602 and NE612. They came from the same wafer.

Then Signetics was bought out by Philips, who evidently continued this practice for a short time, then decided it was rather redundant. So they announced that the production of NE602's has been discontinued and listed it as an obsolete part ... giving QRPers around the world various fits of apoplexy to suicidal tendencies that doomsday had struck. What wasn't well understood is Philips continued to support production of the NE612, as they do today.

Then to make matters worse, disaster struck the Philips plant in Albuquerque in the spring of 2000. A wild grass fire in northwest New Mexico threatened three main electrical lines that run from the "Four Corners" electrical generating plant to Albuquerque. Smoke from the fire caused one of the high-voltage lines to arc, tripping the circuit off line. Virtually the entire electrical load for Albuquerque and southern New Mexico was now transfered to the two remaining feeders, which could not handle the full load, causing brownouts, voltage spikes, etc. until they too failed. Where I live in Socorro, New Mexico, I remember the brownouts hit about 4:15pm, outages on and off until the entire grid went down about 5pm, and stayed off until about 11pm. One of the longest power failures in US history. We just figured it was Y2K about 3 months late. (PS - I worked 40M CW QRP that night by candlelight, and it was the quietest conditions I ever heard on 40M!!! And every QSO I heard seemed to be a QRPer). The extreme voltage fluctations as the feeders were failing caused a transformer at the Philips plant in Albuquerque to catch on fire. I remember seeing it on the TV news, in which they said it caused mostly smoke damage from the burning transformer and burned a couple of storage rooms. That was all-no biggie. Well, it turned out one of the storage rooms that was burned was where they stored the film masters for making the semiconductor dies, and the NE612 film master was now molten emulsion. These film masters were the originals from the old Signetics company. So Philips had to completely redo the artwork for the majority of their IC's. Additionally, it turned out the smoke damage was excessive and the IC fabrication facilities were left unusable. Philips was basically unable to manufacture IC's at the Albuquerque plant for months. It was about 8 months before they got all their wafer machines back on line, which left a huge hole in the semiconductor industry. I know it just about killed several cell phone manufacturers because delivery contracts for parts were suddenly postponed for six to eight months.

The world wide supply of NE602/NE612's virtually dried up during 2000 as a result of this fire and the nearly year backlog of manufacturing quotas. The first run of NE612's in 2 years finally occured in September 2000.This huge shortage of NE612's, combined with the fact that NE602's have been discontinued/obsolete, is what convinved QRPers that these nifty little chips were no more. I was told 20,000 units were manufactured in 2000, or what Philips believes is a 2 year supply. This is also why the release of the K1 (with 5 NE612's!) was delayed from the promised "after Dayton" to late in the year, as were other kits. It just wasn't clear when Philips was going to schedule the NE612's for production.

So yes, the NE602 is dead, but the perfectly compatible NE612 is still available, and Philips has no plans at the present to discontinue that part number.

------------------------------------------------------------------------------------------------------------------------26 November 2006GOOGLE EARTH SPOTS M0HBR'S LONDON ANTENNA!Here's Google Earth's shot of our house in London. I was amazed to be able to see my fishing pole dipole! These are the same fishing poles that supported my 17 meter rotatable dipole in the Azores.

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